Drilling fluid containing chlorosulfonated alpha-olefin copolymers

Abstract

This invention is based upon the finding that certain chlorosulfonated α-olefin copolymers can be beneficially utilized in drilling fluids that are utilized in drilling subterreanean wells. For instance, it has been unexpectedly found that certain chlorosulfonated α-olefin copolymers can be beneficially used as total or partial replacements for organoclays in oil based drilling fluids. The chlorosulfonated a-olefin copolymers that are useful in the practice of this invention are typically chlorosulfonated ethylene/octene copolymers or chlorosulfonated ethylene/butene copolymers. The utilization of chlorosulfonated α-olefin copolymers in oil-based drilling fluids offers (1) long service life at high operating temperatures, (2) minimal formation damage, (3) improved filtration behavior, and (4) highly effective performance at low viscosifier levels. Additionally, the chlorosulfonated α-olefin copolymers utilized in the practice of this invention are soluble in conventional drilling fluid formulations which reduce the level of mixing required in preparation of the drilling fluid formulation. This makes the preparation of the drilling fluid easier, faster and less energy intensive. The chlorosulfonated α-olefin copolymers used in making the drilling fluids of this invention are also free flowing powders which makes them easier to handle than the sulfonated EPDM (ethylene-propylene-diene monomer rubbers) crumbs employed in the drilling fluids of the prior art. The present invention more specifically discloses an oil-based drilling fluid which is comprised of: (a) an organic liquid; (b) water; (c) an emulsifier; (d) a wetting agent; (e) a fluid loss reducing agent; (f) a weighting material; and (g) a chlorosulfonated α-olefin copolymer.